Preparation of Carboxylic Acids and Their Derivatives

Even the sterically hindered 2,6-disubstituted aryl iodide 443 is carbonylated smoothly to give 445. Alkyl iodide present in the alcoholic component 444 remains intact under the carbonylation conditions. This carbonylation reaction is a key reaction in the synthesis of zearalenone (446) [216]. Optimal conditions for technical synthesis of the anthranilic acid derivative 448 from bromide 447 has been studied, and it has been found that A-acetyl protection of 447, which has a chelating effect, is important [217]. Cheaply available chlorides are rather inert [13]. The carbonylation of chloride 449 in the presence of DBU and Nal gives the amide 450 [218], 

Triflates derived from phenols are carbonylated to form aromatic esters by using Pd-Ph3P. The carbonylation of triflates is 500 times faster if DPPP (XLIV) is used [219]. This reaction is a good preparative method of benzoates from phenols and naphthoates from naphthols [220]. Carbonylation of enol triflates derived from ketones and aldehydes affords a,/Cunsaturated esters. The enol triflate in 451 is more reactive than the aryl triflate and the carbonylation proceeds stepwise chemoselectively. At 

Other pseudohalides are carbonylated. Benzoic acid derivatives are prepared from arenediazonium salts at room temperature without addition of a phosphine ligand [223], For example, the acid anhydride 457 is prepared by the carbonylation of the benzenediazonium salt 456 in the presence of AcONa. By this method, nitrobenzene can be converted to benzoic acid indirectly. 

Carbonylation of halides in the presence of primary and secondary amines at 1 atm affords amides. The intramolecular carbonylation of an aryl bromide which has an amino group affords a lactam. The seven-membered lactam 459 (tomaymycin, neothramycin skeletons) is prepared from 458 by this method [224], 

By careful selection of reactions conditions, double carbonylation occurs, which is competitive with monocarbonylation. Utilizing alkylphosphines or DPPB, and secondary amines, the oc-keto amide 460 is obtained with high chemoselectivity [225,226], 

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Cyano-substituted selenophenes are valuable precursors of formyl derivatives.89 They are also used as starting materials for the preparation of carboxylic acids and their derivatives.128 By treating the cyano compounds with hydrogen selenide, selenoloamides (101) were obtained. As shown in... 

Carbonylation is a very important process for the preparation of carboxylic acids (and their derivatives), aldehydes and ketones. It was earlier carried out in presence of transition metal catalysts. 

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